1. Field of the Invention
The present invention relates to a developing apparatus for use in an image forming apparatus.
2. Related Art of the Invention
In the prior art, it is known to provide a recirculating-type developing apparatus in an image forming apparatus, such as a copying machine, employing a two-component developing method. In one such developing apparatus 200 shown in FIG. 8, two transport screws 201 for mixing and transporting developer are rotatably mounted with a partition wall 202 interposed therebetween, and a toner density detect sensor 204 is located in a sidewall 203 of the developing apparatus 200 in close proximity to one of the transport screws 201. The toner density detect sensor 204 is designed to detect the toner density of the developer carried on the transport screw 201. FIG. 8 given here shows a side structural view of the recirculating-type developing apparatus 200, with certain parts omitted for clarity.
In this developing apparatus 200, the developer transported by the transport screws 201, etc. is continually distributed to the surface of a developing sleeve 205, and as the developing sleeve 205 rotates (in the direction shown by arrow in the figure), the thickness of the developer on it is adjusted by means of a doctor blade 206 before the developer is brought into contact with the surface of a photoconductor drum 207. Then, a toner image is formed on the surface of the photoconductor drum 207.
The above construction, however, has had the shortcoming that when the developing apparatus 200 has been used for long periods of time, the same toner particles tend to remain adhering to the surface of the developing sleeve 205, making it difficult to apply the necessary toner to the surface of the photoconductor drum 207 and thus degrading the intended function of the developing sleeve 205. This results in a degradation in copy quality of the copying machine.
In view of the above problem of the prior art developing apparatus, it is an object of the present invention to provide a developing apparatus that can prevent copy quality degradation.